The present invention relates to variable valve actuating apparatuses or systems for controlling opening and closing timings of intake valves and exhaust valves of internal combustion engines.
Japanese Patent Application Publication No. 6-235307 discloses a variable valve actuating system for an internal combustion engine. This variable valve actuating system includes an intake valve timing varying mechanism for varying opening and closing timings of intake valves of the engine, and an exhaust valve timing varying mechanism for varying opening and closing timings of exhaust valves of the engine. A control unit controls the opening and closing timings of the intake valves and exhaust valves in accordance with an operating state of the engine, by hydraulically actuating the intake and exhaust valve timing varying mechanisms.